The invention relates to a trimming device for cutting a cover thread on a multiple needle chainstitch sewing machine.
It is known from British Patent Specification No. 2209542A to catch a cover thread between a spreader and the upper side of a presser foot and to guide it towards a combined catching and cutting device, which is disposed in front of the spreader. This produces a cover thread direction, which points obliquely forwards and which permits secure binding of the cover thread about the needle threads on the workpiece in the case of short starting needle threads, but, because of the structural design, impedes handling of the workpiece during the sewing operation, since the combined catching and cutting device is disposed both to the side of and below the spreader.
A further trimming device is known from published German patent application No. 35 31 595 A1. This "Offenlegungsschrift" describes a moveable cutting knife for cutting the top cover thread, which is provided with a hook edge and which is moved mechanically backwards and forwards between the spreader and the workpiece from a diagonal upper rear direction towards the middle of the cover thread. This device produces long starting needle threads, which may impede some sewing operations. Following termination of sewing, these thread ends must be additionally trimmed in order to obtain a visually acceptable sewn product.
Cutting of the remaining sewing threads at the end of the seam is generally known and is described, for example, in German Patent Specification No. 25 38 916 C2.
It is an object of the invention to provide a trimming device such that, on commencement of sewing, on the one hand only short thread ends project from the workpiece and, on the other hand, handling of the workpiece by the operator during the sewing operation is not impeded.